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/* ************************************************************************** */
/* */
/* ::: :::::::: */
/* render_state.c :+: :+: :+: */
/* +:+ +:+ +:+ */
/* By: cacharle <marvin@42.fr> +#+ +:+ +#+ */
/* +#+#+#+#+#+ +#+ */
/* Created: 2020/01/15 14:40:14 by cacharle #+# #+# */
/* Updated: 2020/01/17 14:48:15 by cacharle ### ########.fr */
/* */
/* ************************************************************************** */
#include "cub3d.h"
/*
** -1 0 1 <-- camera_x
** v v v
** ################
** # | # <-- screen
** # | #
** ################
**
** camera_x is the x column from the camera percpective
** scaling the plane vector and adding it to the direction vector
** to create a vector in the *direction* of the column x.
*/
void rstate_ray(t_state *state, t_render_state *rstate)
{
double camera_x;
camera_x = 2.0 * (double)rstate->x / (double)state->window.width - 1.0;
rstate->ray = vector_add(state->dir, vector_scale(state->plane, camera_x));
}
/*
** delta between each grid unit form the vector percpective
**
** if we have a vector v = [2 3]:
** dx = |v| / v_1
** = sqrt(v_1^2 + v_2^2) / v_1
** = (v_1^2 + v_2^2) / v_1^2
** = 1 + v_2^2 / v_1^2
** Same thing for dy
** dy = |v| / v_2
** = sqrt(v_1^2 + v_2^2) / v_1
** = (v_1^2 + v_2^2) / v_2^2
** = v_1^2 / v_2^2 + 1
**
** This can be simplified (for some obscure reason):
** dx = |1 / v_1|
** dy = |1 / v_2|
*/
void rstate_delta(t_render_state *rstate)
{
rstate->delta.x = vector_norm(rstate->ray) / rstate->ray.x;
rstate->delta.y = vector_norm(rstate->ray) / rstate->ray.y;
}
/*
** first delta between player position and first grid unit
**
** current x and y are the perpendicular distance to the nearest wall,
** we multiply them by their corresponding delta.
** 0 <= perpendicular distance <= 1 is a ratio, how much of the full delta we need to take.
**
** if (rstate->ray.x < 0)
** rstate->probe.x = state->pos.x - rstate->map_pos.x;
** else
** rstate->probe.x = fabs(state->pos.x - rstate->map_pos.x + 1.0);
** if (rstate->ray.y < 0)
** rstate->probe.y = state->pos.y - rstate->map_pos.y;
** else
** rstate->probe.y = fabs(state->pos.y - rstate->map_pos.y + 1.0);
** rstate->probe.x *= rstate->delta.x;
** rstate->probe.y *= rstate->delta.y;
*/
void rstate_init_probe(t_state *state, t_render_state *rstate)
{
rstate->probe = VECTOR_SUB(state->pos, rstate->map_pos);
if (rstate->ray.x > 0)
rstate->probe.x += 1.0;
if (rstate->ray.y > 0)
rstate->probe.y += 1.0;
rstate->probe.x *= rstate->delta.x;
rstate->probe.y *= rstate->delta.y;
}
/*
** Move the probe to it's next iteration by advancing to the nearest square unit
** in the x or y direction.
** This advance is represented both with the
** player/ray percpective and the map pecpective.
*/
void rstate_next_probe(t_render_state *rstate)
{
if (rstate->probe.x < rstate->probe.y)
{
rstate->probe.x += rstate->delta.x;
rstate->map_pos.x += rstate->map_step.x;
}
else
{
rstate->probe.y += rstate->delta.y;
rstate->map_pos.y += rstate->map_step.y;
}
}
/*
** perpendicular distance between the wall hit and the camera plane.
** We don't use euclidean distance because it would cause a fisheye effect.
**
** ====================X========== wall
** | /|
** | <------ / | -----+
** | / | |
** plane | / | <- perpendicular distance
** | | / |
** v | / |
** <-------^----/----------------- camera plane
** | /
** dir -> | /
** | / <- euclidean distance
** |/
** x <- pos
**
** In this case the perpendicular distance (p) is the difference
** of the y-coord of the hit point and the y-coord of the pos + dir vector.
** We use the y component because we hit the wall
** from a south/north percepective,
** if we had hit it form west/east, we would use the x component instead.
*/
double rstate_perp_dist(t_state *state, t_render_state *rstate)
{
double dist;
/* printf("ray [%f %f]\n", rstate->ray.x, rstate->ray.y); */
dist = 1.0;
if (rstate->side == SIDE_NS)
{
dist = rstate->map_pos.y - state->pos.y;
dist += rstate->map_step.y == 1 ? 1 : 0;
dist /= rstate->ray.y;
}
else if (rstate->side == SIDE_WE)
{
dist = rstate->map_pos.x - state->pos.x;
dist += rstate->map_step.x == 1 ? 1 : 0;
dist /= rstate->ray.x;
}
return dist;
/* if (rstate->side == SIDE_NS) */
/* return fabs(rstate->map_pos.y - state->pos.y + state->dir.y); */
/* else if (rstate->side == SIDE_WE) */
/* return fabs(rstate->map_pos.x - state->pos.x + state->dir.x); */
/* return (1.0); */
}
/*
** 0 <= 1 / perp_dist <= 1
** height * (1 / perp_dist) is how much of the screen height do we take
*/
void rstate_line_height(t_state *state, t_render_state *rstate)
{
/* double perp = rstate_perp_dist(state, rstate); */
/* printf("perp %f\n", perp); */
rstate->line_height = (int)((double)state->window.height / rstate_perp_dist(state, rstate));
}
t_image *get_tex(t_state *state, t_render_state *rstate)
{
if (rstate->side == SIDE_NS)
{
if (rstate->probe.y < state->pos.y)
return (state->textures + TEX_NORTH);
else
return (state->textures + TEX_SOUTH);
}
else if (rstate->side == SIDE_WE)
{
if (rstate->probe.x < state->pos.x)
return (state->textures + TEX_WEST);
else
return (state->textures + TEX_EAST);
}
return (NULL);
}
/*
** Since we're drawing each column, all the texels we want to draw on the window
** are on a single column of the texture.
** First we find the x-coord relative to the wall we hit
*/
/* int get_tex_x() */
/* { */
/* //calculate value of wall_x */
/* double wall_x; //where exactly the wall was hit */
/* if (side == 0) wall_x = state->pos.y + perp_dist * ray.y; */
/* else wall_x = state->pos.x + perp_dist * ray.x; */
/* wall_x -= floor(wall_x); */
/* //x coordinate on the texture */
/* int tex_x = (int)(wall_x * (double)texWidth); */
/* if(side == 0 && ray.x > 0) tex_x = texture_width - tex_x - 1; */
/* if(side == 1 && ray.y < 0) tex_x = texture_width - tex_x - 1; */
/* return (tex_x); */
/* } */
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